Many electronic devices now have a touch screen 10 for inputting data or selecting an input from a menu. Such touch screen 10 includes a display screen 12 and a touch sensing system 14 placed on top of the display screen. The touch sensing system 14 includes a transparent sensing circuit for allowing a user to input or make a selection via virtual buttons. When a user touches a virtual button, a signal is sent from the touch sensing circuit to a controller in the electronic device to register an input or selection. For example, the touch sensing system 14 may be a resistive or a capacitive type. A resistive touch screen will require mechanical pressure to be exerted on a virtual button on the touch screen, such as one button of a 4-point or 360 degree directional pad. A capacitive touch screen will not require mechanical pressure to be exerted on a virtual button; it works by the virtual button sensing a capacitance change when a user's linger or thumb touches it. As a touch screen is flat and smooth, activating a virtual button does not give a tactile feedback to a user; lack of a tactile feedback on a touch screen 10 gives a poor sensory experience, especially to a user for playing a game, say on an iPad or smartphone, when the user can rarely take one's eyes away from the screen.
To provide a solution, US publication no. 2011/0157056 by Karpfinger, describes a physical button that provides a tactile feel and a sensed touch on a touch screen. In one embodiment, the button is disposed in a frame. The frame is deformable and when a force on the button is removed, the frame causes the button to revert back to its unactivated position.
In another approach, U.S. Pat. No. 7,391,410 assigned to Sony Ericsson Mobile, describes a joystick that is pivoted on a lid disposed over a touch screen. The joystick has a pin in contact with the touch screen. Movement of the joystick is thus detected on the touch screen.
Despite availability of the above prior art devices, there is still a need for another touch screen activating device that provides tactile feedback to a user, especially a device that is removeably mounted on a touch screen, for example, for a user to play a game or a user to operate a touch screen remote controller for a television set and so on.